Is it safe to relight a furnace pilot light myself?

Furnace makers say yes, in one narrow case: your furnace has a standing pilot, you smell no gas, and you follow the lighting instructions the manufacturer wrote for that model. Carrier calls relighting a standard homeowner task, while sending pilot assembly repairs to a professional.^[1] Lennox says "if your pilot light is out, you can follow the manufacturer's instructions on how to relight it safely."^[2]

That "yes" does not cover a gas smell, a carbon monoxide alarm, a pilot that keeps going out, a furnace with no pilot at all, or anything inside the gas controls.

First, find out whether your furnace has a pilot

Many furnaces have nothing to relight. According to Lennox, "Most modern furnaces manufactured since 2010 do not utilize pilot lights".^[2] Bryant explains the split: "Older furnaces may use a standing pilot light, while modern high-efficiency furnaces generally use electronic ignition systems."^[3] Columbia Gas of Virginia puts it the same way: "some older natural gas appliances could have pilot lights that stay on all the time, while new high-efficiency natural gas furnaces do not have pilot lights."^[4]

The owner's manual or the model label tells you which kind you have. If your furnace uses electronic ignition and will not light, there is no flame for you to light by hand. "If a pilot light repeatedly goes out or an electronic ignition system fails to establish a flame, Bryant recommends professional service rather than repeated attempts to restart the furnace."^[3] For the other reasons a furnace runs without heat, see why a furnace runs but does not heat.

When not to relight it

You smell gas. Gas has no smell of its own; Columbia Gas adds an odorant called mercaptan, which gives a sulfur or rotten-egg-like odor.^[5] If you smell it, leave the pilot alone and get out. Columbia Gas's instructions are plain: "Don't smoke or light a match. Don't open the windows. Don’t use anything that could cause a spark, like a phone, light switch, appliance or flashlight."^[5] From a safe location away from the building, Columbia Gas customers call 911 and the company's emergency number, 1-800-544-5606, which answers 24/7.^[5] Columbia Gas will send someone to check the source of a gas odor free of charge, whether there is a leak or not.^[5] If another company or a propane dealer supplies your gas, use its emergency number instead.

The pilot keeps going out. Columbia Gas says "if your pilot light goes out, it could be a sign that your appliance needs to be inspected and repaired by a qualified professional",^[4] and Bryant notes that "a recurring pilot-light problem can indicate an issue with the thermocouple, gas supply or another component."^[3] If the pilot lights but will not stay lit, Carrier points to a dirty orifice or a faulty thermocouple.^[1]

The pilot will not light, or the flame looks wrong. If the pilot does not light at all, Lennox says there could be a faulty gas valve, and a flickering flame, or one whose base is yellow instead of blue, could mean a blockage.^[2] Either is a job for a technician with the right parts and test equipment.

A carbon monoxide alarm has sounded, or someone feels ill. Carbon monoxide is an odorless, colorless and toxic gas.^[7] EPA's list of indoor sources includes "back-drafting from furnaces" and "worn or poorly adjusted and maintained combustion devices (e.g., boilers, furnaces) if the flue is improperly sized, blocked or disconnected".^[7] Columbia Gas lists "flu-like symptoms including headaches, dizziness, nausea, vomiting, irregular breathing or feeling ill".^[6] If a carbon monoxide alarm sounds or you have those symptoms, leave for fresh air and call 911, and do not go back in until emergency responders say you can.^[6]

Why the rest is a technician's job

The pilot sits on the furnace's gas controls. Lighting it with the manufacturer's procedure is one thing; cleaning the orifice, changing a thermocouple or replacing a gas valve is gas work. Columbia Gas's rule for customers is that "natural gas lines and appliances should never be tampered with",^[4] and Carrier's warning is short: "Attempting DIY fixes on gas components can lead to safety hazards."^[1]

If you are tired of relighting an old standing-pilot furnace every winter, that is a sign of its age as much as a repair. Read should I repair or replace my furnace before paying for a large repair on an old unit.

When to call a licensed pro

Call an HVAC business, and do not try again, if the pilot keeps going out, will not light, will not stay lit, burns yellow, or if you smelled gas at any point. Call 911 and your gas company first for a gas smell or a carbon monoxide alarm.

In Virginia, no individual may engage in, or offer to engage in, work as a tradesman unless licensed, and a tradesman is anyone who does electrical, plumbing or heating, ventilation and air conditioning work for the public for pay. The exception is someone working under the supervision of a tradesman licensed in that specialty.^[8][9] Virginia also licenses liquefied petroleum gas fitters for propane piping, tanks and appliances, but the definition leaves central heating systems to those holding an HVAC or plumbing licence,^[8][9] so a propane furnace is still an HVAC technician's job. Check any business on DPOR's License Lookup^[10] before it starts.

See does an HVAC technician need a licence in Virginia, what happens during a furnace repair visit, and what it costs to fix a furnace that won't heat.

Getting it fixed

Loclis lists DPOR-licensed HVAC businesses with their licence number and class. Find HVAC businesses in Blacksburg or another town, see furnace not heating repairs, or browse more HVAC repair answers.

If the pilot will not stay lit or the furnace will not heat, describe what it is doing once and licensed local HVAC businesses quote the repair.